Icons and more displaying as Squares

Hello! I can’t seem to figure out why some of the icons on my site show up as squares: https://www.burchettssmallenginerepair.com

Some Examples:
– Image “next” and “previous” selectors
– Social Icons (see blog post)

I’m running the Avada theme, so I’m not sure if there’s a specific fix for that theme (I’ve looked).
I believe the font-awesome icons all work (see checkboxes).

Am I missing something obvious? Thanks ??